I don't want to get into a debate about the importance of
documentation, but documentation is really one of the most important
things about software.

Thanks for educating me on the importance of documentation. If you
could also instruct me about **how** it should be improved, not just
**why**, that would be a "giant leap for the mankind".

If you as a developer understand the code, this
doesn't mean the code is usable since most of those who use it are not
developers and do not know how to read the code. Everybody appreciates
the time and effort given by the developers. The administrator guide has
no mention of the overlays (at least not chain) and the man pages do not
give enough description, also the administrator guide could add examples
for some configurations, maybe like those ones being asked in the
mailing list.

I really searched for my question a lot in the list but could not find it.

Did you search the -software for "chain;referral"? I got 51 hits, most
of them pertinent.